In recent years, information terminals such as cell phone using a touch panel have increased. Particularly, buttons other than the touch panel have been minimized for such information terminals. Typically, in the electronic device capable of being input via a touch panel, such as portable music player or cell phone, a user contacts the touch panel to change a sound volume setting value of voice or video data. By way of example, the setting values of sound volume and playback position may be controlled from a slide bar in the touch panel provided on a display part of the electronic device.
The following related arts are known as the electronic device using a touch panel.
For example, Patent Literature 1 describes an acoustic device which sets a sound volume-up region and a sound volume-down region to be spaced from each other in a part overlapping on a sound volume adjustment region image displayed on a display part in a touch panel, sets a plurality of linearly-adjacent sound volume adjustment regions between both the regions, detects an object contact on the regions, and changes an acoustic signal such that a sound volume output from an acoustic output device depending on the detection result is any of sound volumes classified into multiple stages. According to this, there can be provided an acoustic device which enables a user to easily adjust a desired sound volume level when the touch panel is used to adjust the sound volume level.
Patent Literature 2 describes an input operation device which detects a pressing force on a touch surface of a touch panel and controls a reporting unit based on report contents corresponding to the detected pressing force. According to this, there can be provided an input operation device capable of improving user operability.
Patent Literature 3 describes a display device in which two display screens mounting touch panels thereon are adjacently arranged, the display device displaying image data with the two display screen as one screen, detecting a touch point position on each touch panel of the two display screens, and displaying the image data in an enlarged or reduced manner such that a coordinate position of each touch point coincides with each coordinate position in the displayed image data on the two display screens in response to a motion of the detected touch point. According to this, there can be provided a display device capable of easily enlarging/reducing the displayed image by use of the touch panel provided in each display screen when a plurality of display screens are adjacently arranged to enlarge the entire display size.
Patent Literature 4 describes an input device for an electronic device which executes predetermined functions, such as sound volume adjustment function, of inputting a predetermined one-stroke handwriting (such as clockwise circle or counterclockwise circle) from a touch panel, comparing and analyzing a direction changing trend of the input handwriting, and increasing the sound volume for the clockwise circle of the handwriting or decreasing the sound volume for the counterclockwise circle based on the comparing and analyzing of the direction changing trend. According to this, there can be provided an input device which is simple and convenient for operations suitable for operation interface.